Data storage medium and method for the preparation thereof

ABSTRACT

A data storage medium includes a substrate, a reflective metal layer, and a haze-prevention layer between the substrate and the reflective metal layer. The substrate includes an amorphous thermoplastic resin having a heat distortion temperature of at least about 140° C., a density less than 1.7 grams per milliliter, and an organic volatiles content less than 1,000 parts per million measured according to ASTM D4526. The haze-prevention layer includes a material having a volume resistivity of at least 1×10 −4  ohm-centimeters and a tensile modulus of at least about 3×10 5  pounds per square inch. The data storage medium resists hazing of the reflective layer at elevated temperatures.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional ApplicationSerial No. 60/405,609, filed Aug. 23, 2002.

BACKGROUND

[0002] Reflective articles comprising a thermoplastic substrate and areflective metal layer are currently employed in a variety of productapplications, including automotive headlight reflectors and data storagemedia (e.g., data storage discs). Such articles may perform well atambient temperatures, but at the elevated temperatures encountered incertain manufacturing and use conditions, their reflectivity may beimpaired by the formation of haze in the reflective coating.

[0003] There is therefore a need for reflective articles that maintaintheir reflectivity at elevated temperatures.

BRIEF SUMMARY

[0004] One embodiment is a data storage medium improved heat-resistance,comprising: a substrate comprising an amorphous thermoplastic resinhaving a heat distortion temperature of at least about 140° C. measuredat 66 pounds per square inch (psi) according to ASTM D648, a densityless than 1.7 grams per milliliter, and an organic volatiles contentless than 1,000 parts per million measured according to ASTM D4526; areflective metal layer; and a haze-prevention layer interposed betweenthe substrate and the reflective metal layer, wherein thehaze-prevention layer comprises a material having a volume resistivityof at least 1×10⁻⁴ ohm-centimeters measured according to ASTM D257 at25° C. and a tensile modulus of at least about 3×10⁵ pounds per squareinch measured according to ASTM D638 at 25° C.

[0005] Other embodiments, including a method of preparing the datastorage medium, are described in detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006]FIG. 1 is an exploded view of a reflective article 10 comprising athermoplastic substrate 20, a reflective metal layer 30, and ahaze-prevention layer 40.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] One embodiment is a data storage medium, comprising: a substratecomprising an amorphous thermoplastic resin having a heat distortiontemperature of at least about 140° C. measured at 66 psi according toASTM D648, a density less than 1.7 grams per milliliter, and an organicvolatiles content less than 1,000 parts per million measured accordingto ASTM D4526; a reflective metal layer; and a haze-prevention layerinterposed between the substrate and the reflective metal layer, whereinthe haze-prevention layer comprises a material having a volumeresistivity of at least 1×10⁻⁴ ohm-centimeters measured according toASTM D257 at 25° C. and a tensile modulus of at least about 3×10⁵ poundsper square inch measured according to ASTM D638 at 25° C.

[0008] During the commercial development of reflectors for automotiveheadlights, it was sometimes observed that reflectors prepared by directmetalization of a thermoplastic substrate would initially exhibitexcellent reflectivity, but under conditions of use, hazing of thereflective surface would occur, leading to failure of the part. Throughextensive research on a variety of materials, the present inventors havediscovered that haze-formation under high-temperature conditions can bereduced or eliminated by interposing between the thermoplastic substrateand the reflective metal layer a haze-prevention layer comprising amaterial having a volume resistivity of at least 1×10⁻⁴ ohm-centimetersmeasured according to ASTM D257 at 25° C. and a tensile modulus of atleast about 3×10⁵ pounds per square inch measured according to ASTM D638at 25° C.

[0009] The substrate comprises an amorphous thermoplastic resin having aheat distortion temperature of at least about 140° C., preferably atleast about 170° C., more preferably at least about 185° C., still morepreferably at least about 200° C., measured at 66 psi according to ASTMD648. The amorphous thermoplastic also has a density less than 1.7grams/milliliter (g/mL), preferably less than 1.6 g/mL, more preferablyless than 1.5 g/mL. The density of the amorphous thermoplastic resin maybe determined at 25° C. according to ASTM D792. The amorphousthermoplastic resin is thus less dense than bulk molding compounds thathave often been used to form reflective articles. When the reflectivearticle is a headlight reflector, the use of the amorphous resin reducesthe weight of the headlight thereby contributes to weight reductionsthat allow more vehicle miles per gallon of fuel. The amorphousthermoplastic further has an organic volatiles content less than 1,000parts per million by weight, preferably less than 750 parts per millionby weight, more preferably less than 500 parts per million by weight,measured according to ASTM D4526. As specified in ASTM D4526, thevolatiles are determined by sampling a headspace in equilibrium with thethermoplastic at 90° C., and they are quantified using flame ionizationdetection. The organic volatiles content is thus lower than that of bulkmolding compounds, which may contain high concentrations of residualmonomers that outgas at elevated temperatures and decrease thereflectivity of the reflective metal layer. Suitable thermoplasticresins include, for example, polyetherimides, polyetherimide sulfones,polysulfones, polyethersulfones, polyphenylene ether sulfones,poly(arylene ether)s, polycarbonates, polyester carbonates,polyarylates, and the like, and mixtures thereof. These thermoplasticsand methods for their preparation are known in the art.

[0010] Preferred polyetherimides include those comprising structuralunits of the formula (I)

[0011] wherein the divalent T moiety bridges the 3,3′, 3,4′, 4,3′, or4,4′ positions of the aryl rings of the respective aryl imide moietiesof formula (I); T is —O— or a group of the formula —O-Z-O—; Z is adivalent radical selected from the group consisting of formulae (II)

[0012] wherein X is a member selected from the group consisting ofdivalent radicals of the formulae (III)

[0013] wherein y is an integer of 1 to about 5, and q is 0 or 1; R is adivalent organic radical selected from (a) aromatic hydrocarbon radicalshaving 6 to about 20 carbon atoms and halogenated derivatives thereof,(b) alkylene radicals having 2 to about 20 carbon atoms, (c)cycloalkylene radicals having 3 to about 20 carbon atoms, and (d)divalent radicals of the general formula (IV)

[0014] where Q is a covalent bond or a member selected from the groupconsisting of formulae (V)

[0015] where y′ is an integer from 1 to about 5.

[0016] In the formulas above, when X or Q comprises a divalent sulfonelinkage, the polyetherimide may be considered a polyetherimide sulfone.

[0017] Generally, useful polyetherimides have a melt index of about 0.1to about 10 grams per minute (g/min), as measured by American Societyfor Testing Materials (ASTM) D1238 at 337° C., using a 6.6 kilogramweight.

[0018] In a preferred embodiment, the polyetherimide resin has a weightaverage molecular weight of about 10,000 to about 150,000 atomic massunits (AMU), as measured by gel permeation chromatography usingpolystyrene standards. Such polyetherimide resins typically have anintrinsic viscosity greater than about 0.2 deciliters per gram measuredin m-cresol at 25° C. An intrinsic viscosity of at least about 0.35deciliters per gram may be preferred. Also, an intrinsic viscosity of upto about 0.7 deciliters per gram may be preferred.

[0019] Included among the many methods of making the polyetherimideresin are those described, for example, in U.S. Pat. Nos. 3,847,867 toHeath et al., 3,850,885 to Takekoshi et al., 3,852,242 and 3,855,178 toWhite, and 3,983,093 to Williams et al.

[0020] In a preferred embodiment, the polyetherimide resin comprisesstructural units according to formula (I) wherein each R isindependently paraphenylene or metaphenylene and T is a divalent radicalof the formula (VI).

[0021] A particularly preferred polyetherimide resin is the reactionproduct formed by melt polymerization of2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride with one ormore of paraphenylene diamine and metaphenylene diamine. Thepolyetherimides are commercially available from General Electric Companyas ULTEM® resins, including, for example, ULTEM® 1000, ULTEM® 1010,ULTEM® 6000, ULTEM® XH6050, and ULTEM® CRS5000. Additional descriptionof polyetherimide polymers may be found, for example, in ASTM 5205,Standard Classification System for Polyetherimide (PEI) Materials.

[0022] Polysulfones suitable for use in the thermoplastic substrate arepolymeric comprising repeating units having at least one sulfone group.Polysulfones and methods for their preparation are well known in the artand described, for example, in U.S. Pat. No. 3,642,946 to Grabowski etal.; and Kirk-Othmer, Encyclopedia of Chemical Technology, SecondEdition, Vol. 16, pp. 272-281 (1968). Representative polymers of thistype include polysulfones, polyether sulfones, and polyphenyl sulfones.

[0023] The polysulfones that may be utilized in the instant inventioncontain at least one recurring structural unit represented by thegeneral formula (VII)

[0024] wherein each occurrence of Ar is independently unsubstitutedphenylene or phenylene substituted with phenyl, C₁-C₁₂ alkyl, C₁-C₁₂alkoxy, halogen, nitro, or the like; and each occurrence of A isindependently a direct carbon-to-carbon bond, C₁-C₁₂ alkylidene, C₃-C₈cycloalkylidene, carbonyl sulfoxide, sulfur, sulfone, azo, imino,oxygen, or the like.

[0025] The polysulfones of Formula (VII) are preferably derived fromdichlorodiphenyl sulfones reacted with bisphenols. A second group ofsulfones represented by Formula I is one in which each Ar is phenyleneand A is sulfone. A third major group of polysulfones represented byFormula I are those wherein each Ar is phenylene and A is oxygen, i.e.,the polyarylethersulfones. When Ar is phenylene, it should preferably beeither meta or para and may be substituted in the ring positions withC₁-C₆ alkyl groups, C₁-C₆ alkoxy groups, or the like. Particularlyuseful polysulfones are those derived from disulfonyl chlorides such as4,4-biphenyldisulfonyl chloride reacted with 4,4′-dihydroxydiphenylether.

[0026] The polyarylethersulfones, including polyphenylene ethersulfones, contain at least the following recurring structural units

[0027] wherein R, R¹ and R² are independently selected from C₁-C₆ alkyl,C₄-C₈ cycloalkyl, and halogen radicals; W is a C₂-C₈ alkylene, a C₁-C₈alkylidene, a cycloalkylene or cycloalkylidene radical containing from 4to about 16 ring carbon atoms, or the like; b is 0 or 1; and n, n1, andn2 are independently 0, 1, 2, 3, or 4. Additional description ofpolysulfone may be found, for example, in ASTM D6394, StandardSpecification for Sulfone Plastics (SP).

[0028] Suitable poly(arylene ether)s include polyphenylene ether (PPE)and poly(arylene ether) copolymers; graft copolymers; poly(aryleneether) ether ionomers; and block copolymers of alkenyl aromaticcompounds, vinyl aromatic compounds, and poly(arylene ether), and thelike; and combinations comprising at least one of the foregoing; and thelike. Poly(arylene ether)s are known polymers comprising a plurality ofstructural units of the formula

[0029] wherein for each structural unit, each Q¹ is independentlyhalogen, primary or secondary C₁-C₈ alkyl, phenyl, C₁-C₈ haloalkyl,C₁-C₈ aminoalkyl, C₁-C₈ hydrocarbonoxy, or C₂-C₈ halohydrocarbonoxywherein at least two carbon atoms separate the halogen and oxygen atoms;and each Q² is independently hydrogen, halogen, primary or secondaryC₁-C₈ alkyl, phenyl, C₁-C₈ haloalkyl, C₁-C₈ aminoalkyl, C₁-C₈hydrocarbonoxy, or C₂-C₈ halohydrocarbonoxy wherein at least two carbonatoms separate the halogen and oxygen atoms. Preferably, each Q¹ isalkyl or phenyl, especially C₁₋C₄ alkyl, and each Q² is independentlyhydrogen or methyl.

[0030] Both homopolymer and copolymer poly(arylene ether)s are included.The preferred homopolymers are those comprising 2,6-dimethylphenyleneether units. Suitable copolymers include random copolymers comprising,for example, such units in combination with2,3,6-trimethyl-1,4-phenylene ether units or copolymers derived fromcopolymerization of 2,6-dimethylphenol with 2,3,6-trimethylphenol. Suchcopolymers of 2,6-dimethylphenol and 2,3,6-trimethylphenol, especiallythose containing about 5 to about 50 weight percent of units derivedfrom 2,3,6-trimethylphenol, are particularly preferred for their heatresistance. Also included are poly(arylene ether)s containing moietiesprepared by grafting vinyl monomers or polymers such as polystyrenes, aswell as coupled poly(arylene ether) in which coupling agents such as lowmolecular weight polycarbonates, quinones, heterocycles and formalsundergo reaction in known manner with the hydroxy groups of twopoly(arylene ether) chains to produce a higher molecular weight polymer.Poly(arylene ether)s of the present invention further includecombinations of any of the above, including blends of poly(aryleneether)s and polystyrene resins.

[0031] The poly(arylene ether) generally has a number average molecularweight of about 3,000 to about 40,000 atomic mass units (AMU) and aweight average molecular weight of about 20,000 to about 80,000 AMU, asdetermined by gel permeation chromatography. The poly(arylene ether)generally may have an intrinsic viscosity of about 0.2 to about 0.6deciliters per gram (dL/g) as measured in chloroform at 25° C. Withinthis range, the intrinsic viscosity may preferably be up to about 0.5dL/g, more preferably up to about 0.47 dL/g. Also within this range, theintrinsic viscosity may preferably be at least about 0.3 dL/g. It isalso possible to utilize a high intrinsic viscosity poly(arylene ether)and a low intrinsic viscosity poly(arylene ether) in combination.Determining an exact ratio, when two intrinsic viscosities are used,will depend on the exact intrinsic viscosities of the poly(aryleneether)s used and the ultimate physical properties desired.

[0032] The poly(arylene ether)s are typically prepared by the oxidativecoupling of at least one monohydroxyaromatic compound such as2,6-xylenol or 2,3,6-trimethylphenol. Catalyst systems are generallyemployed for such coupling. They typically contain at least one heavymetal compound such as a copper, manganese or cobalt compound, usuallyin combination with various other materials. Suitable methods forpreparing poly(arylene ether)s are described, for example, in U.S. Pat.Nos. 3,306,874 and 3,306,875 to Hay, and 4,011,200 and 4,038,343 toYonemitsu et al.

[0033] Suitable polycarbonates may be prepared by reacting a dihydricphenol with a carbonate precursor, such as phosgene, a haloformate, or acarbonate ester. Generally, such carbonate polymers possess recurringstructural units of the formula

[0034] wherein A is a divalent aromatic radical of the dihydric phenolemployed in the polymer producing reaction. Preferably, the carbonatepolymers used to provide the resinous mixtures of the invention have anintrinsic viscosity (as measured in methylene chloride at 25° C.) ofabout 0.30 to about 1.00 dL/g. The dihydric phenols employed to providesuch aromatic carbonate polymers may be mononuclear or polynucleararomatic compounds, containing as functional groups two hydroxyradicals, each of which is attached directly to a carbon atom of anaromatic nucleus. Typical dihydric phenols include, for example,2,2-bis(4-hydroxyphenyl)propane (bisphenol A); hydroquinone; resorcinol;2,2-bis(4-hydroxyphenyl)pentane; 2,4′-(dihydroxydiphenyl)methane;bis(2-hydroxyphenyl)methane; bis(4-hydroxyphenyl)methane;bis(4-hydroxy-5-nitrophenyl)methane; 1,1 -bis(4-hydroxyphenyl)ethane;3,3-bis(4-hydroxyphenyl)pentane; 2,2-dihydroxydiphenyl;2,6-dihydroxynaphthalene; bis(4-hydroxydiphenyl)sulfone;bis(3,5-diethyl-4-hydroxyphenyl)sulfone;2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane; 2,4′-dihydroxydiphenylsulfone; 5′-chloro-2,4′-dihydroxydiphenyl sulfone;bis(4-hydroxyphenyl)diphenyl sulfone; 4,4′-dihydroxydiphenyl ether;4,4′-dihydroxy-3,3′-dichlorodiphenyl ether;4,4-dihydroxy-2,5-dihydroxydiphenyl ether; and the like.

[0035] Other dihydric phenols suitable for use in the preparation ofpolycarbonate resins are described, for example, in U.S. Pat. Nos.2,999,835 to Goldberg, 3,334,154 to Kim, and 4,131,575 to Adelmann etal.

[0036] These aromatic polycarbonates can be manufactured by knownprocesses, such as, for example and as mentioned above, by reacting adihydric phenol with a carbonate precursor, such as phosgene, inaccordance with methods set forth in the above-cited literature and inU.S. Pat. No. 4,123,436 to Holub et al., or by transesterificationprocesses such as are disclosed in U.S. Pat. No. 3,153,008 to Fox, aswell as other processes known to those skilled in the art.

[0037] It is also possible to employ two or more different dihydricphenols or a copolymer of a dihydric phenol with a glycol or with ahydroxy- or acid-terminated polyester or with a dibasic acid in theevent a carbonate copolymer or interpolymer rather than a homopolymer isdesired. Branched polycarbonates are also useful, such as are describedin U.S. Pat. No. 4,001,184 to Scott. Also, there can be utilized blendsof linear polycarbonate and a branched polycarbonate. Moreover, blendsof any of the above materials may be employed in the practice of thisinvention to provide the aromatic polycarbonate.

[0038] These polycarbonates may be branched or linear and generally willhave a weight average molecular weight of about 10,000 to about 200,000AMU, preferably from about 20,000 to about 100,000 as measured by gelpermeation chromatography. The polycarbonates of the invention canemploy a variety of end groups to improve performance. Bulky monophenols, such as cumyl phenol, are preferred.

[0039] Suitable polycarbonates further include those derived frombisphenols containing alkyl cyclohexane units. Such polycarbonates havestructural units corresponding to the structure

[0040] wherein R^(a)-R^(d) are each independently hydrogen, C₁-C₁₂hydrocarbyl, or halogen; and R^(e)-R^(i) are each independentlyhydrogen, C₁-C₁₂ hydrocarbyl. As used herein, “hydrocarbyl” refers to aresidue that contains only carbon and hydrogen. The residue may bealiphatic or aromatic, straight-chain, cyclic, bicyclic, branched,saturated, or unsaturated. The hydrocarbyl residue, when so statedhowever, may contain heteroatoms over and above the carbon and hydrogenmembers of the substituent residue. Thus, when specifically noted ascontaining such heteroatoms, the hydrocarbyl residue may also containcarbonyl groups, amino groups, hydroxyl groups, or the like, or it maycontain heteroatoms within the backbone of the hydrocarbyl residue.Alkyl cyclohexane containing bisphenols, for example the reactionproduct of two moles of a phenol with one mole of a hydrogenatedisophorone, are useful for making polycarbonate resins with high glasstransition temperatures and high heat distortion temperatures. Suchisophorone bisphenol-containing polycarbonates have structural unitscorresponding to the structure

[0041] wherein R^(a)-R^(d) are as defined above. These isophoronebisphenol based resins, including polycarbonate copolymers madecontaining non-alkyl cyclohexane bisphenols and blends of alkylcyclohexyl bisphenol containing polycarbonates with non-alkyl cyclohexylbisphenol polycarbonates, are supplied by Bayer Co. under the APEC tradename and described, for example, in U.S. Pat. No. 5,034,458 to Serini etal.

[0042] Suitable thermoplastic resins further include “polyarylates,”which is the common term referring to polyesters of aromaticdicarboxylic acids and bisphenols. Polyarylate copolymers includingcarbonate linkages in addition to the aryl ester linkages, known aspolyester-carbonates, are also suitable. These resins may be used aloneor in combination with each other or more preferably in combination withbisphenol polycarbonates. These resins can be prepared in solution or bymelt polymerization from aromatic dicarboxylic acids or their esterforming derivatives and bisphenols and their derivatives. Suitabledicarboxylic acids are iso- and terephthalic acid, their esters or acidchlorides. A preferred bisphenol is bisphenol A or its diacetatederivative. Polyester carbonates and polyarylates may also containlinkages derived from hydroxy carboxylic acids such as hydroxy benzoicacid. The most preferred polyester-carbonates and polyarylates areamorphous resins derived from bisphenol A and mixtures of isophthalicand terephthalic acid. Suitable polyarylates and their preparation aredescribed, for example, in U.S. Pat. No. 4,663,421 to Mark. Suitablepolyester-carbonates and their preparation are described, for example,in U.S. Pat. Nos. 3,169,121 to Goldberg, and 4,156,069 to Prevorsek etal.

[0043] In one embodiment, the substrate comprises at least about 50% byweight, preferably at least about 80% by weight, more preferably atleast about 90% by weight, still more preferably at least about 95% byweight, of the thermoplastic resin.

[0044] In one embodiment the substrate comprises, in addition to thethermoplastic resin, an inorganic filler such as, for example, talc,mica, clay, titanium dioxide, zinc oxide, zinc sulfide, wollastonite, orthe like, or a mixture thereof.

[0045] In another embodiment, the substrate is substantially free ofinorganic filler. “Substantially free of inorganic filler” is definedherein as comprising less than 0.1 weight percent of inorganic filler.It may be preferred that the substrate comprises less than 0.01 weightpercent of inorganic filler.

[0046] The substrate resin may further contain additives to improve meltprocessing, molding or part stability. Useful additives includelubricants and mold release agents, such as aliphatic esters, forexample pentaerythritol tetrastearate, or polyolefins, for example highdensity polyethylene. Stabilizers, such as aryl phosphite and hinderedphenols may also be blended with the substrate resin. Other additivesinclude compounds to reduce static charge build up. If employed in thesubstrate, it is important to select such additives so that they arethermally stable, show low volatility and do not contribute to hazing inthe metallized article.

[0047] The dimensions of the substrate will be dictated by the use ofthe reflective article. For example, when the reflective article is aheadlight reflector, it may have a thickness of about 0.1 to about 20millimeters in the dimension perpendicular to the haze-prevention layerand the reflective metal layer; within this range, the thickness maypreferably be at least about 0.5 millimeters, more preferably at leastabout 1 millimeter; also within this range, the thickness may preferablybe up to about 10 millimeters, more preferably up to about 8millimeters. As another example, when the reflective article is a datastorage disc, it may have a thickness of about 0.1 to about 5millimeters in the dimension perpendicular to the haze-prevention layerand the reflective metal layer; within this range, the thickness maypreferably be at least about 0.5 millimeters, more preferably at leastabout 1 millimeter; also within this range, the thickness may preferablybe up to about 4 millimeters, more preferably up to about 3 millimeters.

[0048] The reflective article comprises a reflective metal layer. Metalssuitable for use in the reflective metal layer include the metals ofGroups IIIA, IIIB, IVB, VB, VIB, VIIB, VIII, IB, and IIB of the periodictable. Mixtures and alloys of these metals may also be used. Preferredmetals include aluminum, silver, gold, nickel, palladium, platinum,copper, and the like, and alloys comprising at least one of theforegoing metals. Aluminum and its alloys are particularly preferredmetals for the reflective metal layer.

[0049] The reflective metal layer may be formed using methods known inthe art, including sputtering, vacuum metal deposition, vapor arcdeposition, plasma chemical vapor deposition, thermal vapor metaldeposition, and ion plating.

[0050] The reflective metal layer may have a thickness of about 1 toabout 1000 nanometers. Within this range, the thickness may preferablybe at least about 10 nanometers, more preferably at least about 20nanometers. Also within this range, the thickness may preferably be upto about 500 nanometers, more preferably up to about 200 nanometers.

[0051] The reflective article comprises a haze-prevention layerinterposed between the substrate and the reflective metal layer. Thehaze-prevention layer comprises comprising a material having a volumeresistivity of at least 1×10⁻⁴ ohm-centimeters measured according toASTM D257 at 25° C. and a tensile modulus of at least about 3×10⁵ poundsper square inch (2068 megapascals) measured according to ASTM D638 at25° C. The volume resistivity may preferably be at least 1×10⁻²ohm-centimeters, more preferably at least 1 ohm-centimeter. The tensilemodulus may preferably be at least about 5×10⁵ pounds per square inch(3447 megapascals), more preferably at least about 8×10⁵ pounds persquare inch (5516 megapascals), still more preferably at least about1×10⁶ pounds per square inch (6895 megapascals). In a preferredembodiment, the haze prevention layer has a tensile modulus of at least3×10⁵ pounds per square inch (2068 megapascals) measured at the heatdistortion temperature of the amorphous resin employed in the substrate.In this embodiment, if the substrate includes more than one amorphousresin, the tensile modulus is measured at the lowest heat distortiontemperature of any amorphous resin. The haze-prevention layer ispreferably non-metallic, and plasma-polymerized haze-prevention layersare highly preferred. In addition to meeting the above resistivitylimitation, the non-metallic haze-prevention layer may preferablycomprise less than 1 weight percent total of zero-valent metals.

[0052] In one embodiment, the haze-prevention layer comprises aplasma-polymerized organosilicone. A plasma-polymerized organosilicone,sometimes called a hydroxy silicon carbide or silicon oxy carboncoating, is a product of plasma deposition of a silicon precursor havingthe formula

[0053] wherein each R is independently hydrogen, C₁-C₆ alkyl, C₂-C₆alkenyl, C₃-C₆ alkenyl alkyl, C₆-C₁₈ aryl, or the like; n is 0 to about100; m is 1 to about 100; and X is —O— or —NH—.

[0054] Preferred organosilicone compounds include

[0055] and the like, and mixtures thereof.

[0056] Plasma polymerization of the organosilicone may take place in thepresence of a small amount of oxygen that may be incorporated into thecoating. The plasma-polymerized organosilicone haze-reduction layer canbe formed from a variety of plasma deposition techniques includingplasma assisted or enhanced chemical vapor deposition (PECVD, PACVD)using plasma sources of radio frequency (RF), microwave (MW),inductively coupled plasma (ICP), electron cyclotron resonance (ECR),hollow cathode, thermal plasma, expanding thermal plasma (ETP), andplasma arcs or jets. In a preferred embodiment, the haze reduction layeris deposited by ETP as described in patents U.S. Pat. Nos. 6,420,032 tolacovangelo and 6,397,776 to Yang et al.

[0057] In one embodiment, the haze-prevention layer comprises at leastabout 50 weight percent, preferably at least about 80 weight percent,more preferably at least about 90 weight percent, still more preferablyat least about 95 weight percent of the plasma-polymerizedorganosilicone, based on the total weight of the haze-prevention layer.

[0058] In another embodiment, the haze-prevention layer comprisesdiamond-like carbon. A haze-prevention layer comprising diamond-likecarbon may be formed from plasma-assisted chemical vapor deposition oforganic monomer as described, for example, in U.S. Pat. Nos. 5,506,038to Knapp et al., and 5,527,596 and 5,508,092 to Kimock et al.

[0059] In another embodiment, the haze-prevention layer comprises acolloidal silica composition comprising colloidal silica dispersed in asilanol-, acrylic-, or methacrylic-derived polymer system. For example,the colloidal silica composition may be an acidic dispersion ofcolloidal silica and hydroxylated silsesquioxane in an alcohol-watermedium. More particularly, the coating composition may be a dispersionof colloidal silica in a lower aliphatic alcohol-water solution of asilanol having the formula RSi(OH)₃ in which R may be, for example,C₁-C₃ alkyl, vinyl, 3,3,3-trifluoropropyl, gamma-glycidoxypropyl,gamma-methacryloxypropyl, or the like. Preferably, at least 70 percentof the silanol is CH₃Si(OH)₃. The composition may comprise, for example,10 to 50 weight percent solids consisting essentially of 10 to 70 weightpercent colloidal silica and 30 to 90 weight percent of a partialcondensate of the silanol (i.e., a hydroxylated silsesquioxane), thecomposition containing sufficient acid to provide a pH in the range of3.0 to 6.0. Suitable coating compositions and their preparation aredescribed, for example, in U.S. Pat. Nos. 3,986,997 to Clark and5,346,767 to Tilley et al.

[0060] As another example, the colloidal silica composition may be asilica containing coating composition comprising about 10 to 50 weightpercent solids dispersed in a water/aliphatic alcohol mixture whereinthe solids comprise about 10 to 70 weight percent ammoniumhydroxide-stabilized colloidal silica and about 30 to 90 weight percentof a partial condensate derived from an organotrialkoxy silane of theformula R′Si(OR)₃ wherein R′ may be, for example, C₁-C₃ alkyl, C₆-C₁₃aryl, or the like, and R may be, for example, C₁-C₈ alkyl, C₆-C₂₀ aryl,or the like, the composition having a pH of from about 7.1 to about 7.8.Suitable coating compositions and their preparation are described, forexample, in U.S. Pat. Nos. 4,624,870 to Blair and 5,346,767 to Tilley etal.

[0061] As a third example, the colloidal silica composition may be anultraviolet light curable coating comprising about 1 to about 60 weightpercent colloidal silica; about 1 to about 50 weight percent of thematerial produced by the hydrolysis of silyl acrylate; and about 25 toabout 90 weight percent of an acrylate monomer. The composition may,optionally, further include about 0.1 to about 5 weight percent of a UVphotoinitiator. Preferred compositions are derived from aqueouscolloidal silica, 2-methacryloxy-propyltrimethoxysilane,hexanediolacrylate, and a photosensitizing amount of a photoinitiator.Suitable compositions and their preparation are described, for example,in U.S. Pat. Nos. 4,491,508 to Olson et al. and 5,346,767 to Tilley etal.

[0062] As a fourth example, the colloidal silica composition may be anultraviolet light curable coating comprising 100 parts by weight ofcolloidal silica; 5-500 parts by weight of an acryloxy-functional silaneor glycidoxy-functional silane; 10-500 parts by weight of a non-silylacrylate; and a catalytic amount of an ultraviolet light sensitivephotoinitiator. Preferred compositions comprise aqueous colloidalsilica, methacryloxypropyl trimethoxysilane, hexanedioldiacrylate, aglycidyloxy functional silane, and a cationic photoinitiator. Thesecompositions and their preparation are disclosed in U.S. Pat. Nos.4,348,462 to Chung, 4,491,508 to Olson, and 5,346,767 to Tilley et al.

[0063] In one embodiment, the haze-prevention layer comprises at leastabout 50 weight percent, preferably at least about 80 weight percent,more preferably at least about 90 weight percent, still more preferablyat least about 95 weight percent of the colloidal silica composition,based on the total weight of the haze-prevention layer.

[0064] In one embodiment, the haze-prevention layer comprises athermoset resin. Suitable thermoset resins include thermoset polyesterresins, thermoset epoxy resins, novolac resins, melamine resins, and thelike. Such resins are well known in the art and commercially available.

[0065] In one embodiment, the haze-prevention comprises at least about50 weight percent, preferably at least about 80 weight percent, morepreferably at least about 90 weight percent, still more preferably atleast about 95 weight percent of the thermoset resin, based on the totalweight of the haze-prevention layer.

[0066] The thickness of the haze-prevention layer will depend on itscomposition, but it is generally about 10 nanometers to about 100micrometers. Within this range, the thickness may preferably be at leastabout 20 nanometers, more preferably at least about 40 nanometers. Alsowithin this range, the thickness may preferably be up to about 50micrometers, more preferably up to about 10 micrometers. Depending onthe material employed in the haze-prevention layer, it may be possibleto use thinner haze-prevention layers. For example, when thehaze-prevention layer comprises a plasma-polymerized organosilicone, thethickness may be less than 100 nanometers, preferably less than 90nanometers, more preferably less than 80 nanometers, still morepreferably less than 70 nanometers.

[0067] Although the substrate is well suited for direct application of ahaze-prevention layer, it is also possible to pre-coat the substratewith a primer before applying the haze-prevention layer. It may also beadvantageous to further coat the reflective article with a clear, hardprotective layer to protect the reflective metal layer from scratching,oxidation, or related problems. The protective layer may, preferably,exhibit a percent transmittance greater than 90 percent measurednanometers according to ASTM D1003. The protective layer may,preferably, exhibit a yellowness index less than 5 measured according toASTM D1925. Suitable compositions and methods for preparing protectivemetal oxide layers are described, for example, in U.S. Pat. Nos.6,110,544 to Yang et al., and 6,379,757 B1 to Iacovangelo. Thus, in oneembodiment, the reflective article includes a substrate, ahaze-prevention layer, a reflective layer, and a protective layer,wherein the haze-prevention layer is interposed between substrate andthe reflective layer, and the reflective layer is interposed between thehaze-prevention layer and the protective layer.

[0068] In a preferred embodiment, the reflective article comprises asurface having a reflectivity of at least 80%, more preferably at leastabout 85%, even more preferably at least about 90%, measured accordingto ASTM D523. In a highly preferred embodiment, the reflective articlecomprises a surface having a reflectivity of at least 80%, morepreferably at least about 85%, even more preferably at least about 90%,after 15 minutes exposure to the lowest heat distortion temperature ofany thermoplastic resin in the substrate.

[0069]FIG. 1 presents an exploded perspective view of a section of areflective article 10. Haze-prevention layer 40 is interposed betweensubstrate 20 and reflective metal layer 30.

[0070] The reflective article may be used, for example, as an automotiveheadlight reflector, a reflector incorporated into a projector lamp, amirror of any shape and curvature. Headlight reflectors and theirpreparation is described, for example, in U.S. Pat. Nos. 4,210,841 toVodicka et al., 5,503,934 to Maas et al., and 6,355,723 B1 to van Baalet al. Data storage media and methods for their preparation aredescribed, for example, in U.S. Pat. Nos. 5,783,653 to Okamoto et al.,and 6,436,503 to Cradic et al., as well as U.S. patent applicationPublication Nos. 2002-0048691 A1 to Davis et al., 2002-0094455 A1 toFeist et al., 2002-0197438 A1 to Hay et al., and 2003-0044564 A1 to Driset al.

[0071] In an embodiment preferred for its simplicity, the reflectivearticle consists essentially of: a substrate comprising an amorphousthermoplastic resin having a heat distortion temperature of at leastabout 140° C. measured at 66 psi according to ASTM D648, a density lessthan 1.7 grams per milliliter, and an organic volatiles content lessthan 1,000 parts per million measured according to ASTM D4526; areflective metal layer; and a haze-prevention layer interposed betweenthe substrate and the reflective metal layer, wherein thehaze-prevention layer comprises a material having a volume resistivityof at least 1×10⁻⁴ohm-centimeters measured according to ASTM D257 at 25°C. and a tensile modulus of at least about 3×10⁵ pounds per square inchmeasured according to ASTM D638 at 25° C.

[0072] In a preferred embodiment, the reflective article is a datastorage medium that comprises: a substrate comprising a polysulfone oran isophorone bisphenol-containing polycarbonate resin having a glasstransition temperature of at least about 170° C., a density less than1.7 grams per milliliter, and an organic volatiles content less than1,000 parts per million measured according to ASTM D4526; a reflectivemetal layer comprising aluminum; and a plasma-polymerized organosiliconehaze-prevention layer interposed between the substrate and thereflective metal layer, wherein the haze-prevention layer comprises aplasma-polymerized organosilicone having a volume resistivity of atleast 1×10⁻² ohm-centimeters measured according to ASTM D257 at 25° C.and a tensile modulus of at least about 5×10⁵ pounds per square inchmeasured according to ASTM D638.

[0073] Another embodiment is a method for preparing a data storagemedium, comprising: applying a haze-prevention layer to a surface of asubstrate, wherein the haze-prevention layer comprises a material havinga volume resistivity of at least 1×10⁻⁴ ohm-centimeters measuredaccording to ASTM D257 at 25° C. and a tensile modulus of at least about3×10⁵ pounds per square inch measured according to ASTM D638, andwherein the substrate comprises an amorphous thermoplastic resin havinga heat distortion temperature of at least about 140° C. measuredaccording to ASTM D648, a density less than 1.7 grams per milliliter,and an organic volatiles content less than 1,000 parts per millionmeasured according to ASTM D4526; and applying a reflective metal layerto a surface of the haze-prevention layer.

[0074] The invention is further illustrated by the followingnon-limiting examples. Examples of the invention are designated bynumbers. Comparative examples are designated by letters.

COMPARATIVE EXAMPLE A, EXAMPLES 1-3

[0075] Injection molded 102 millimeter diameter×3.2 millimeter thickdiscs of polyetherimide (ULTEM 1010 from GE Plastics Co.) were coatedusing the following process: samples were pumped down in a vacuumchamber and glow cleaned at a power setting of 3.0 kW for 180 seconds at0.023 torr. The parts were the pre-coated with a haze-reducingplasma-polymerized organosilicone coating made by introducinghexamethyldisiloxane (HMDSO) into the chamber and creating a plasma. Thepressure was 0.027 to 0.036 torr, and the power was 3.2 kilowatts (kW).The plasma-polymerized organosilicone coating time was varied from 2 to4 to 8 minutes to give a plasma-polymerized organosilicone coatingthickness of about 40 to about 145 nm. The parts were then coated withabout 100 nm of aluminum at 0.00005 torr. A post metallizationprotective top-coat was then applied at 0.027 torr, power 3.2 kW for 180seconds. Coated samples were then subject to a post glow for 180 secondsat 3.2 kW at 0.018 torr and were taken from the chamber.

[0076] In order to test the haze-prevention performance of the samplescoated with plasma-polymerized organosilicone, the parts were heatedfrom 198 to 210° C. in 2° C. increments and observed for haze. Resultsare shown in Table 1. Comparative Example A, the metallizedpolyetherimide (PEI) control with no plasma-polymerized organosiliconehaze-prevention layer, showed haze at 204° C. Example 1, with a twominute plasma-polymerized organosilicone haze-prevention layer, resistedhaze formation until 208° C. Example 2, with a 4 minuteplasma-polymerized organosilicone haze-prevention layer, resisted hazeup to 210° C. Example 3, with an eight minute plasma-polymerizedorganosilicone haze-prevention layer, showed a haze resistance up to210° C. TABLE 1 Plasma-Polymerized Organosilicone Coating Haze Onset °C. Thickness Example A PEI-No plasma- 204 None polymerizedorganosilicone under-coat Example 1 PEI-2 minute 208  41 nmplasma-polymerized or- ganosilicone un- der-coat Example 2 PEI-4 minute210  64 nm plasma-polymerized or- ganosilicone under-coat Example 3PEI-8 minute 210 145 nm plasma-polymerized or- ganosilicone under-coat

COMPARATIVE EXAMPLES B-I, EXAMPLES 4-11

[0077] Disks, 102 millimeter×3.2 millimeter, of various high glasstransition temperature (T_(g)) thermoplastics resins (Table 2) wereinjection molded and metallized as described above. Control examples(B-I) were coated with a reflective aluminum coating of about 100 nmthat was then protected with a top-coat layer. Examples of the invention(4-11) were first coated for about four minutes with a haze reducinghydroxy silicon carbide layer generated from the plasma deposition ofHMDSO. The hydroxy silicon carbide layer thickness was about 64 nm. Thesamples were then coated with a reflective layer of aluminum andtop-coated with a protective layer.

[0078] Table 2 shows the high Tg resins tested. Heat distortiontemperature (HDT) was measured according to ASTM D648. Glass transitiontemperature was measured by differential scanning calorimetry (DSC)according to ASTM D3418. TABLE 2 HDT @ 66 psi Thermoplastic Resin T_(g)(° C.) (° C.) Polyethersulfpone, ULTRASON E2010 220 208 from BASF Co.Bisphenol A Polysulfone, EDEL P-1700 185 178 from Solvay Co. Bisphenol APolycarbonate, LEXAN 141 148 140 from GE Plastics Co. Isophoronebisphenol based polycarbon- 184 174 ate, APEC 9359 from Bayer Co.Isophorone bisphenol based polycarbon- 206 190 ate, APEC 9379 from BayerCo. 75:25 blend of Polyetherimide and Poly- 215 & 175 197 carbonateester, ULTEM ATX200 from GE Plastics Polyetherimide with mold release,217 207 ULTEM 1010M from GE Plastics Co. Polyetherimide Sulfone, ULTEMXH6050 249 237 from GE Plastics Co.

[0079] The coated samples were then heated in an air-circulating oven toexamine haze formation. The initial temperature was about 20° C. belowthe glass transition temperature of each different resin. Thetemperature was raised in 2° C. increments until hazing was observed.Samples were held for about 90 minutes at each temperature. For eachtype of resin the control sample and the haze reduced samples wereheated under the same conditions. Heating temperatures were varied toreflect the heat capability (T_(g) and HDT) of each individual resin orresin mixture.

[0080] Table 3 shows the temperature at which haze formation is firstobserved for control samples B-I, in which substrates were coated withjust a reflective aluminum layer, and samples of the invention, 4-11,including a substrate, a plasma-polymerized organosiliconehaze-prevention layer, and a reflective metal layer. Note that for eachresin the plasma-polymerized organosilicone underlayer (haze-preventionlayer) imparts an increased resistance to hazing; the onset of hazing isseen at a higher temperature. TABLE 3 Only In- Cont- reflective ven-Reflective layer with rol layer tion plasma-polymerized Ex- Onset Ex-organosilicone am- Haze am- underlayer Thermoplastic Resin ple (° C.)ple Onset Haze (° C.) Polyethersulfone B 206 4 216 Bisphenol A Polysulf-C 178 5 182 one Bisphenol A Polycar- D 139 6 143 bonate Isophoronebisphenol E 173 7 178 based polycarbonate, APEC 9359 Isophoronebisphenol F 184 8 194 based polycarbonate, APEC 9379 75:25 blend ofPoly- G 196 9 198 etherimide and Poly- ester carbonate Polyetherimidewith H 204 10 210 mold release Polyetherimide Sulf- I 221 11 225 one

COMPARATIVE EXAMPLES J AND K

[0081] Two polycarbonate plaques (LEXAN® 140, obtained from GeneralElectric Company) having thicknesses of 1.52 and 6.35 millimeters weremetallized with aluminum by DC magnetron sputtering at 70 watts and 8millitorr for 20 minutes to produce a reflective layer thickness ofabout 100-200 nanometers. The metallized samples were placed in anair-circulating oven for various lengths of time at increasingtemperatures. At an oven temperature of 125° C., samples did not hazeafter 48 hours, but at 138° C., samples became hazy after about 10 to 20minutes. Haze was observed visually. Selected samples were also examinedby optical microscopy.

EXAMPLES 12 AND 13

[0082] The procedure of Comparative Examples J and K was followed,except that the polycarbonate plaques were pre-coated with anacrylic-modified colloidal silica composition before metalization. Theacrylic-modified colloidal silica composition was obtained as an AS4000suspension from GE Silicones and applied by flow coating and thermalcuring to produce a cured haze reducing layer coating thickness of about6-8 micrometers. After metallization with aluminum, samples showed noevidence of haze after up to 24 hours at temperatures as high as 145° C.Although there was no hazing at 145° C., samples warped and theacrylic-modified colloidal silica cracked at that temperature. Thissystem, though successful at reducing haze, was not optimized for otherperformance features.

COMPARATIVE EXAMPLE L

[0083] Plaques of polyetherimide (ULTEM 1000) having thicknesses of 3.2millimeters were metallized according with aluminum according to theprocedure of Comparative Examples J and K to create a reflective layerthickness of about 200 nanometers. Samples were tested at oventemperatures of 195 to 210° C. The samples developed haze after timesvarying from 48 hours (at 195° C.) to 3 minutes (at 210° C.).

EXAMPLE 14

[0084] A 3.2 millimeter thick plaque of polyetherimide (ULTEM® 1000) wascoated with a plasma-polymerized organosilicone layer to yield a coatingthickness of about 2 micrometers. The plasma deposition was carried outusing an expanding argon thermal plasma at 70 amps with 1.65 standardliters per minute (slpm) of argon. Deposition was carried out in twocoating passes each about 1 micrometer thick. Oxygen andoctamethylcyclotetrasiloxane (D4) were fed downstream of the expandingplasma through a ring injector. The feed rate of D4 was 0.19 slpm inboth passes, and the feed rate of oxygen was 0.3 and 0.8 slpm in thefirst and second passes, respectively. The sample was then metallized bysputtering aluminum onto the plasma-polymerized organosilicone surfaceto yield a reflective layer thickness of about 200 nanometers. Thesample was oven tested as described above. No hazing was observed attemperatures up to 220° C.

[0085] While the invention has been described with reference to apreferred embodiment, it will be understood by those skilled in the artthat various changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include all embodiments falling within the scope of the appendedclaims.

[0086] All cited patents, patent applications, and other references areincorporated herein by reference in their entirety.

1. A data storage medium, comprising: a substrate comprising anamorphous thermoplastic resin having a heat distortion temperature of atleast about 140° C. measured at 66 pounds per square inch according toASTM D648, a density less than 1.7 grams per milliliter, and an organicvolatiles content less than 1,000 parts per million measured accordingto ASTM D4526; a reflective metal layer; and a haze-prevention layerinterposed between the substrate and the reflective metal layer, whereinthe haze-prevention layer comprises a material having a volumeresistivity of at least 1×10⁻⁴ ohm-centimeters measured according toASTM D257 at 25° C. and a tensile modulus of at least about 3×10⁵ poundsper square inch measured according to ASTM D638 at 25° C.
 2. The datastorage medium of claim 1, wherein the amorphous thermoplastic resin isselected from polyetherimides, polyetherimide sulfones, polysulfones,polyethersulfones, polyphenylene ether sulfones, poly(arylene ether)s,polycarbonates, polyester carbonates, polyarylates, and mixturesthereof.
 3. The data storage medium of claim 1, wherein the amorphousthermoplastic resin comprises a polysulfone or an isophoronebisphenol-containing polycarbonate.
 4. The data storage medium of claim1, wherein the substrate is substantially free of inorganic filler. 5.The data storage medium of claim 1, wherein the substrate has athickness of about 0.1 to about 20 millimeters in a dimensionperpendicular to the haze-prevention layer and the reflective metallayer.
 6. The data storage medium of claim 1, wherein the reflectivemetal layer comprises a metal selected from aluminum, silver, gold,nickel, palladium, platinum, copper, and alloys thereof.
 7. The datastorage medium of claim 1, wherein the reflective metal layer comprisesaluminum.
 8. The data storage medium of claim 1, wherein the reflectivemetal layer has a thickness of about 10 to about 1000 nanometers.
 9. Thedata storage medium of claim 1, wherein the haze-prevention layercomprises a plasma-polymerized organosilicone.
 10. The data storagemedium of claim 9, wherein the organosilicone has the formula

wherein each occurrence of R is independently hydrogen, C₁-C₆ alkyl,C₂-C₆ alkenyl, C₃-C₆ alkenyl alkyl, or C₆-C₁₈ aryl; n is 0 to 100; m is1 to 100; and X is —O— or —NH—.
 11. The data storage medium of claim 9,wherein the organosilicone is octamethyl(cyclotetrasiloxane),hexamethyl(cyclotrisiloxane), tetramethyldisiloxane,hexamethyldisiloxane, octamethyltrisiloxane, vinyltriethoxysilane,vinyltrimethoxysilane cyclotetra(methylvinylsiloxane),cyclotri(methylvinylsiloxane), hexamethyldisilazane, or a mixturethereof.
 12. The data storage medium of claim 1, wherein thehaze-prevention layer comprises diamond-like carbon.
 13. The datastorage medium of claim 1, wherein the haze-prevention layer comprises acolloidal silica composition comprising colloidal silica dispersed in asilanol-, acrylic-, or methacrylic-derived polymer system.
 14. The datastorage medium of claim 1, wherein the haze-prevention layer comprises athermoset resin selected from thermoset polyester resins, thermosetepoxy resins, novolac resins, and melamine resins.
 15. The data storagemedium of claim 1, wherein the haze-prevention layer has a thickness ofabout 100 nanometers to about 100 micrometers.
 16. The data storagemedium of claim 1, further comprising a protective layer having apercent transmittance of at least 90% measured according to ASTM D1003at 25° C.; wherein the reflective layer is interposed between thehaze-prevention layer and the protective layer.
 17. The data storagemedium of claim 1, comprising a surface with a reflectivity of at least80% measured according to ASTM D523.
 18. A data storage medium,comprising: a substrate comprising a polysulfone or an isophoronebisphenol-containing polycarbonate resin having a glass transitiontemperature of at least about 170° C., a density less than 1.7 grams permilliliter, and an organic volatiles content less than 1,000 parts permillion measured according to ASTM D4526; a reflective metal layercomprising aluminum; and a haze-prevention layer interposed between thesubstrate and the reflective metal layer, wherein the haze-preventionlayer comprises a plasma-polymerized organosilicone having a volumeresistivity of at least 1×10⁻² ohm-centimeters measured according toASTM D257 at 25° C. and a tensile modulus of at least about 5×10⁵ poundsper square inch measured according to ASTM D638 at 25° C.
 19. The datastorage medium of claim 19, further comprising a protective layer havinga percent transmittance of at least 90% measured according to ASTM D1003at 25° C.; wherein the reflective layer is interposed between thehaze-prevention layer and the protective layer.
 20. A method forpreparing a data storage medium, comprising: applying a haze-preventionlayer to a surface of a substrate, wherein the haze-prevention layercomprises a material having a volume resistivity of at least 1×10⁻⁴ohm-centimeters measured according to ASTM D257 at 25° C. and a tensilemodulus of at least about 3×10⁵ pounds per square inch measuredaccording to ASTM D638 at 25° C., and wherein the substrate comprises anamorphous thermoplastic resin having a heat distortion temperature of atleast about 140° C. measured at 66 pounds per square inch according toASTM D648, a density less than 1.7 grams per milliliter, and an organicvolatiles content less than 1,000 parts per million measured accordingto ASTM D4526; and applying a reflective metal layer to a surface of thehaze-prevention layer.
 21. The method of claim 20, further comprisingapplying a protective layer to the reflective metal layer; wherein theprotective layer has a percent transmittance of at least 90% measuredaccording to ASTM D1003.